Simulink.BusElement

Specify properties of elements of buses

Description

A Simulink.BusElement object is an element of a Simulink.Bus object that validates the properties of an element in a bus. When you simulate or update a model, Simulink^® checks whether the properties specified by the BusElement object match the properties specified by the corresponding bus elements.

BusElement objects exist only within the Bus object. You can specify a Bus object, but not a BusElement object, as a data type.

To create and modify Bus and BusElement objects in the base workspace or a data dictionary, you can use the Bus Editor, Model Explorer, or MATLAB^® commands. You cannot store Bus objects in model workspaces.

Creation

You can create a BusElement object in multiple ways.

• To programmatically create a BusElement object, use the Simulink.BusElement function (described here).

• To interactively create a BusElement object, use the Bus Editor or Model Explorer.

• To create BusElement objects from blocks in a model, MATLAB data, and external C code, see Create Bus Objects Programmatically.

Syntax

be = Simulink.BusElement

Description

be = Simulink.BusElement returns a BusElement object with default property values.

Properties

Name — Name of element

'a' (default) | character vector

Name of element, specified as a character vector.

Note

To validate the properties of a signal against a BusElement object, the signal name must be a valid identifier that starts with an alphabetic character or underscore (_), followed by alphanumeric characters or underscores.

Data Types: char | string

Complexity — Numeric type of element

'real' (default) | 'complex'

Numeric type of the element, specified as 'real' or 'complex'.

Data Types: char | string

Dimensions — Dimensions of element

1 (default) | scalar | vector

Dimensions of element, specified as a scalar or vector.

To use symbolic dimensions in generated code, see Implement Dimension Variants for Array Sizes in Generated Code (Embedded Coder).

Data Types: double

DataType — Data type of element

'double' (default) | character vector | string scalar

Data type of element, specified as a character vector or string scalar.

Click the Show data type assistant button to display the Data Type Assistant, which helps you set the data type attributes. For more information, see Specify Data Types Using Data Type Assistant.

You can specify any of these options:

• Built-in Simulink data type — For example, specify 'single' or 'uint8'. See Data Types Supported by Simulink.

• Fixed-point data type — Use the fixdt function. For example, specify 'fixdt(1,16,0)'.

• Enumerated data type — Use the name of the type preceded by Enum:. For example, specify 'Enum: myEnumType'.

• Bus data type — Use the name of the Simulink.Bus object preceded by Bus:. For example, specify 'Bus: myBusObject'.

• Value type — Use the name of the Simulink.ValueType object preceded by ValueType:. For example, specify 'ValueType: windVelocity'.

• Custom data type — Use a MATLAB expression that specifies the type. For example, you can specify a Simulink.NumericType object whose DataTypeMode property is set to a value other than 'Fixed-point: unspecified scaling'.

Specifying a Simulink.Bus object allows you to create Bus objects that specify hierarchical buses (that is, buses that contain other buses).

When you specify a Simulink.ValueType or Simulink.Bus object, the object defines more than the data type. The object also defines properties such as Min, Max, and Unit. The property values specified by the ValueType object override the corresponding property values specified by a block. For example, suppose a block sets Unit to ft/s. When the Data type of the block specifies a ValueType object that has m/s as its unit, the block uses m/s instead of ft/s.

Data Types: char | string

Min — Minimum value of element

[] (default) | scalar

Minimum value of the element, specified as a scalar. This value must be a finite real double scalar or, if the element is a bus, the value must be empty, [].

Data Types: double

Max — Maximum value of element

[] (default) | scalar

Maximum value of the element, specified as a scalar. This value must be a finite real double scalar or, if the element is a bus, the value must be empty, [].

Data Types: double

DimensionsMode — Specify how to handle size of element

'Fixed' (default) | 'Variable'

Specify how to handle size of element, specified as 'Fixed' or 'Variable'.

Data Types: char | string

Unit — Physical unit for expressing element

'' (default) | character vector

Physical unit for expressing element, specified as a character vector.

For more information, see Unit Specification in Simulink Models.

Example: 'inches'

Data Types: char | string

Description — Bus element description

'' (default) | character vector

Bus element description, specified as a character vector. Use the description to document information about the BusElement object, such as the kind of signal it applies to. This information does not affect Simulink processing.

Data Types: char | string

Examples

Create Bus Objects from Arrays

Create a hierarchy of Bus objects using arrays. Array indexing lets you create and access multiple elements in an array. Dot notation lets you access property values.

Create two BusElement objects, named Chirp and Sine, in the base workspace.

elems(1) = Simulink.BusElement;
elems(1).Name = 'Chirp';

elems(2) = Simulink.BusElement;
elems(2).Name = 'Sine';

Create a Bus object, named NestedBus, that uses the elements defined in the elems array.

NestedBus = Simulink.Bus;
NestedBus.Elements = elems;

Create two more BusElement objects, named NestedBus and Step. To have NestedBus represent a Bus object, specify a Bus object data type.

clear elems

elems(1) = Simulink.BusElement;
elems(1).Name = 'NestedBus';
elems(1).DataType = 'Bus: NestedBus';

elems(2) = Simulink.BusElement;
elems(2).Name = 'Step';

Create the bus at the top of the bus hierarchy that uses the elements defined in the elems array.

TopBus = Simulink.Bus;
TopBus.Elements = elems;

You can view the created objects in the Bus Editor.

buseditor

Compatibility Considerations

Simulink.BusElement objects no longer support the SampleTime property

Errors starting in R2020b

The SampleTime property of Simulink.BusElement objects is no longer supported.

BusElement objects that specify a sample time cause an error during compile. To remove the sample time specification from a BusElement object, set its SampleTime to -1.

Simulink.Bus.cellToObject continues to accept cell arrays that specify sample time for bus elements. Simulink.Bus.objectToCell, Simulink.Bus.save, and Simulink.Bus.createObject continue to return cell arrays or arrays that include the sample time when it is noninherited. When the sample time is inherited (-1), they omit it. Similarly, the Bus Editor and Model Explorer omit the sample time when it is inherited.

To specify the sample time for an element of a bus, use the SampleTime block parameter of corresponding blocks. For example, you can use In Bus Element, Out Bus Element, and Signal Specification blocks to specify sample time.

Simulink.BusElement objects will no longer support the SamplingMode property

Not recommended starting in R2016b

In R2016b, the SamplingMode property of Simulink.BusElement objects was removed. Scripts that use the SamplingMode property of Simulink.BusElement objects continue to work. Simulink.Bus.cellToObject continues to require the SamplingMode field and Simulink.Bus.objectToCell continues to include the sampling mode in the output cell arrays.

In a future release, support for the SamplingMode property will be removed.

To specify whether a signal is sample-based or frame-based, define the sampling mode of input signals at the block level instead of at the signal level.